import ResizeObserver from 'resize-observer-polyfill';

const isServer = typeof window === 'undefined';

/* istanbul ignore next */
function resizeHandler(entries: any[]) {
   for (const entry of entries) {
      const listeners = entry.target.__resizeListeners__ || [];
      if (listeners.length) {
         listeners.forEach((fn: () => any) => {
            fn();
         });
      }
   }
}

/* istanbul ignore next */
export function addResizeListener(element: any, fn: () => any) {
   if (isServer) return;
   if (!element.__resizeListeners__) {
      element.__resizeListeners__ = [];
      element.__ro__ = new ResizeObserver(resizeHandler);
      element.__ro__.observe(element);
   }
   element.__resizeListeners__.push(fn);
}

/* istanbul ignore next */
export function removeResizeListener(element: any, fn: () => any) {
   if (!element || !element.__resizeListeners__) return;
   element.__resizeListeners__.splice(element.__resizeListeners__.indexOf(fn), 1);
   if (!element.__resizeListeners__.length) {
      element.__ro__.disconnect();
   }
}

export function triggerWindowResize() {
   const event = document.createEvent('HTMLEvents');
   event.initEvent('resize', true, true);
   (event as any).eventType = 'message';
   window.dispatchEvent(event);
}
